In a medium pot over medium-heat, add in the 2 tablespoons butter. Once melted, ass in the onion, papaya, garlic, and serrano pepper. Cook for 5-7 minutes, or until the onion is tender and translucent.
Add in the cornstarch and Worcestershire sauce. Cook for 1 minute
Stir in the peanut butter, pumpkin pie spice, honey, and lime juice (if using). Cook for another minute.
Carefully add in the milk and vegetable broth and mix until well combined.
Bring to a boil, then reduce to medium-low heat and cook for 10 minutes, or until the soup has thickened.
Remove from the heat and allow to cool for 5 minutes.
Using an immersion blender or blender, blend the mixture until velvety smooth.
Serve with garnishes of your choice and warm bread.